Generators not available in Display Blocks

Not sure if this is a bug, missed or there is a reason for it. Bt the BS Generators are not available to add inside a display Block.

Screen Shot 2020-03-04 at 2.35.08 PM1762×1330 247 KB

But I can generate them outside the display block and then move them inside the block and they work fine. So I don’t see any reason they are not available?